In article , Joanne
writes

Thanks, Alan. Would yellowing of leaves be a symptom of over-fertilisation?
The leaves on my Tumbler tomatoes have turned completely bright yellow, but
they haven't dropped off, and have no other markings. There are lots of
flowers and some small green tomatoes on the plant. I wasn't sure if the
yellow leaves were too much fertiliser, too much water or too much heat.

More likely to be too much water. The soil needs to be moist, not wet.

--
Alan & Joan Gould - North Lincs.